The present invention relates generally to food waste disposers and, more particularly, to a grinding mechanism or assembly for a food waste disposer.
Although food waste disposers are widely available, manufacturers continue to optimize the grinding operation of such disposers. To perform the grinding operation, conventional disposers typically include a rotating grind plate. The rotating grind plate has grinding lugs attached to the plate. The food waste delivered to the rotating grind plate is forced by the grinding lugs against a stationary shredder ring. The stationary shredder ring has teeth that grind the food waste into particulate matter sufficiently small to pass from above the rotating plate to below the grinding plate via gaps between the teeth outside the periphery of the rotating plate. The particulate matter then passes to a discharge outlet and into the drain pipe.
The fineness and speed of the grind are important considerations in designing the grinding mechanism for a disposer. A manufacturer must consider the demands of a wide variety of food waste with varying properties (i.e., soft, hard, stringy, leafy, and resilient). The types of food waste have changed over the years. Due to healthier diets, consumers tend to eat more fruits and vegetables. This results in food waste having a soft, stringy, leafy, and resilient consistency. Additionally, the modern diet increased the use of white meat. The waste from meat is typically bone. Although the bones from white meat are typically not as durable or difficult to grind than bones from red meat, the bones from white meat tend to splinter. The grinding mechanism must be adequate for all types of food waste.
The type and geometry of the grinding lugs affect the fineness and speed of the grind. Grinding lugs may either be stationary (fixed lugs) or free to rotate (swivel lugs). Early food waste disposers used fixed lugs One example of a disposer with fixed lugs is disclosed in U.S. Pat. No. 4,128,210 (Brenner et al.). There, a fixed impeller or lug extends upwardly and is rigidly attached to the rotating grinding plate. The geometry of the fixed impeller or lug includes a series of steps. The steps rise inwardly toward the center of the rotating grinding plate. Another example of a disposer with fixed lugs is disclosed in U.S. Pat. No. 5,340,036 (Riley), which is owned by the assignee of the present application. There, fixed impellers or lugs are used in a dry waste disposer. In one embodiment, the geometry of the fixed grinding impeller or lug is sloped where the slope rises or increases inwardly toward the center of the rotating grinding plate. In other embodiments, the geometry of the fixed grinding impeller or lug is in a z-shaped or c-shaped configuration. A further embodiment includes a flat grinding impeller or lug. Again, the impeller or lug is rigidly fixed to the rotating plate.
Today, disposers typically use swivel lugs. A food waste disposer having swivel lugs is disclosed in U.S. Pat. No. 6,007,006 (Engel et al.), which is owned by the assignee of the present application and incorporated herein by reference in its entirety. The disposer may be mounted in a well-known manner in the drain opening of a sink using mounting members of the type disclosed in U.S. Pat. No. 3,025,007 (Weiczorek), which is owned by the assignee of the present application and also incorporated herein by reference in its entirety.
As shown in FIG. 1, a conventional disposer includes an upper food conveying section 20, a lower motor section 22, and a central grinding section 24 disposed between the food conveying section 20 and the motor section 22. The food conveying section 20 includes a housing 26 that forms an inlet 28 at its upper end for receiving food waste and water. The housing 26 also forms an inlet 30 for passing water discharged from a dishwasher (not shown). The housing 26 has diverters 96 that are shaped to points 97. The food conveying section 20 conveys the food waste to the central grinding section 24. The motor section 22 includes an induction motor 32 imparting rotational movement to a motor shaft 34. The motor 32 is enclosed within a motor housing 36 having an upper end frame 38, a metal lower end frame 40, and a bent metal stator band 42 extending between the upper and lower end frames 38 and 40.
The grinding section 24 shows a typical grinding plate with swivel lugs. The swivel lug grind system in FIG. 1 has a circular rotating plate or disc 48, a pair of swivel lugs 72, and a stationary shredder ring 46. The plate 48 is mounted to the motor shaft 34 of the motor section 22. The swivel lugs 72 are fastened to the plate 48, but are free to rotate relative to the rotating plate 48. The grinding section 24 includes a housing 52. The housings 26 and 52 are fastened to the lower end frame 40 by a plurality of bolts 54.
As shown in FIGS. 2 and 3, the shredder ring 46, which includes a plurality of spaced teeth 58, is fixedly attached to an inner surface of the housing 52. In the operation of the food waste disposer, the food waste delivered by the food conveying section 22 to the grinding section 24 is forced by the swivel lugs 72 against the teeth 58 of the shredder ring 46. The edges of the teeth 58 grind the food waste into particulate matter sufficiently small to pass from above the grinding plate 48 to below the grinding plate 48 via gaps between the teeth 58 outside the periphery of the plate 48. Due to gravity, the particulate matter that passes through the gaps between the teeth 58 drops onto the upper end frame 38 and, along with water injected into the disposer, is discharged through a threaded discharge outlet 98 into a tailpipe 97. As shown in FIG. 1, the tailpipe 97 may be connected to the discharge outlet 98 by an off-the-shelf plumbing nut 99. There are other known ways to connect a food waste disposer to a tailpipe 97 as explained in U.S. Pat. No. 6,007,006 (Engel et al.).
Although the food waste disposer in FIG. 1 operates efficiently and effectively, it has been found, through the present invention, that a fixed lug grind system can provide a finer grind by optimizing the design of the grind elements.
The problem of jamming is another important consideration in designing the grinding operation. Prior food waste disposers with fixed lugs were known for jamming. Jamming occurs when hard objects such as bones or broken pieces of flatware enter the food waste disposer and get stuck between the rotating grinding elements and the stationary shredder ring. In an attempt to resist jams, the prior art tried to increase the rotational speed of the rotating grind elements or capacitor start. This required increasing the horsepower of the motor, however, and resulted in additional costs of the disposer.
Additionally, to resist jams, the prior art attempted to add swivel lugs to the rotating grinding plate. Although the food waste disposer in FIG. 1 with swivel lugs reduces jams, it has been found, through the present invention, that jamming can also be reduced using fixed lugs by modifying the profile of the lugs without increasing horsepower or capacitor start.
The use of swivel lugs has disadvantages. For example, swivel lugs produce a noisier grinding operation. Moreover, the use of swivel lugs creates a problem known as xe2x80x9cstuckxe2x80x9d lugs. This happens when a food particle (typically a bone fragment or splinter) lodges itself beneath the lug and prevents the lug from moving. A xe2x80x9cstuckxe2x80x9d lug can cause imbalances, resulting in further noise and a degradation of the grind performance. Additionally, when a swivel lug is xe2x80x9cstuck,xe2x80x9d the food waste is more coarse, which can result in clogged drains.
The use of swivel lugs also increases the chances of xe2x80x9criding.xe2x80x9d Riding occurs when food particles rotate at the same speed as the grind elements without being ground. Swivel lugs promote riding because they comply to the motion of the food particle without forcing the particle to be comminuted. The prior art has attempted to solve this problem by decreasing shredder lug height, increasing rotational speeds, and modifying the swivel lugs. Although some methods have reduced the chances of riding, the problem has not been eliminated.
Thus, a need exists for a grinding assembly which has the advantages of both a fixed and rotating lug type without disadvantages of either.
To that end, the present invention provides a grinding mechanism or assembly for a food waste disposer, the grinding mechanism being enclosed in a housing of the food waste disposer. The grinding mechanism includes a shredder plate assembly and a stationary shredder ring. The shredder plate assembly has an upper rotating plate and a lower lug support plate. The lower lug support plate has a body portion and at least one fixed shredder lug integrally formed with the body portion. The upper rotating plate has at least one key slot for receiving the fixed shredder lug. The stationary shredder ring is fixed to the housing of the food waste disposer and has a plurality of teeth. The shredder plate assembly is mounted on a motor shaft that rotates by a motor. The fixed shredder lug forces food waste against the teeth of the stationary shredder ring to grind the food waste into particulate matter.
The profile of the fixed shredder lug may include a vertical toe, a notch and a heel. The heel has a slope that decreases inwardly toward the center of the lower lug support plate. The lower lug support plate may further include at least one fixed tumbling spike integrally formed with the body portion of the lower lug support plate. The fixed tumbling spike assist in the movement of the food waste. The upper rotating plate has a key hole to receive the fixed tumbling spike.
The lower lug support plate may also include a strengthening rib, positive locator, or pumping fingers. The positive locators stabilize the shredder plate assembly and transfer torque from the lower lug support plate to the upper rotating plate. The pumping fingers protrude below the lower lug support plate and may protrude the outer diameter of the lower lug support plate. The pumping fingers improve the fineness of the grind performance as well as increase pumping pressure through a discharge outlet of the food waste disposer.
The upper rotating plate may also include strengthening ribs, drain holes, under-cutters or ramps. The under-cutters protrude beyond the outer diameter of the lower lug support plate and improve the fineness of the grind performance. The ramps are located on the leading edge of the slot that receives the fixed shredder lug and close the void immediately in front of the shredder lug.
The stationary shredder ring may also include diverters and breakers to cause the food waste to tumble, reducing the chances of xe2x80x9criding.xe2x80x9d The stationary shredder ring may be assembled using a TOX(copyright) round joint. The benefit of using a TOX(copyright) round joint is that it can act as a breaker for the stationary shredder ring.
The shredder plate assembly and a stationary shredder ring may be formed using stamping methods, powdered metal methods, injection molding methods, or casting methods.
In another embodiment, the present invention is a food waste disposer that includes an upper food conveying section, a lower motor section and a central grinding section. The upper food conveying section has a first housing forming an inlet for receiving food waste. The lower motor section has a motor for imparting rotational movement to a motor shaft. The central grinding section is disposed between the food conveying section and the motor section. The grinding section has a second housing, a shredder plate assembly and a stationary shredder ring. The shredder plate assembly is mounted to the motor shaft and has an upper rotating plate and a lower lug support plate. The stationary shredder ring has a plurality of teeth and is attached to the second housing. The lower lug support plate has a plurality of fixed shredder lugs to force the food waste against the teeth of the stationary shredder ring to grind the food waste into particulate matter.
The first housing may have a dishwasher inlet and a pair of diverters. The diverters may be rounded and/or smooth in shape and located adjacent to the dishwasher inlet. The second housing may form a discharge outlet having a threaded outer surface adapted to threadably engage a threaded inner surface of a plumbing nut to connect a tailpipe to the discharge outlet.
In yet another embodiment, the present invention is a food waste disposer that includes an upper food conveying section, a lower motor section and a central grinding section. The upper food conveying section has a first housing forming an inlet for receiving food waste. The lower motor section has a motor for imparting rotational movement to a motor shaft and a motor housing that encloses the motor. The central grinding section is disposed between the food conveying section and the motor section. The grinding section has a grinding mechanism and a second housing. The grinding mechanism includes a stationary shredder ring and a shredder plate assembly. The stationary shredder ring has a plurality of teeth and is attached to the second housing. The shredder plate assembly is mounted to the motor shaft and has at least one tumbling spike and a plurality of fixed shredder lugs. The tumbling spike assists in the movement of the food waste. The fixed shredder lugs force the food waste against the teeth of the stationary shredder ring to grind the food waste into particulate matter.
In a further embodiment, the present invention is a grinding mechanism for a food waste disposer that is enclosed in a housing of the food waste disposer. The grinding mechanism comprises a shredder plate assembly and a stationary shredder ring. The shredder plate assembly has at least one fixed shredder lug and at least one tumbling spike. The shredder lug has a vertical toe, a notch and a heel. The heel has a slope that decreases inwardly toward the center of the shredder plate assembly. The stationary shredder ring is fixed to the housing of the food waste disposer and has a plurality of teeth. The fixed shredder lug forces the food waste against the teeth of the stationary shredder ring to grind the food waste into particulate matter. The shredder plate assembly may be formed from stamping methods, powdered metal methods, injection molding methods, or casting methods.
In still another embodiment, the present invention includes a method of manufacturing a food waste disposer that has a grinding mechanism. The grinding mechanism has a shredder plate assembly and a stationary shredder ring. The shredder plate assembly includes an upper rotating plate and a lower lug support plate. The method includes the steps of forming the upper rotating plate, forming the lower lug support plate, and assembling the shredder plate assembly from the upper rotating plate and the lower support plate. The method further includes the steps of forming a stationary shredder ring, providing an enclosure, and attaching the stationary shredder ring to the enclosure. Additionally, the method includes providing a motor for imparting rotational movement to a motor shaft and mounting the shredder plate assembly to the motor shaft. The enclosure is positioned to encompass the grinding mechanism.
The step of forming the upper rotating plate and the lower lug support plate may include cold stamping the component from a sheet or strip of metal, although other methods may be used such as powdered metal methods, injection molding methods, and casting methods. The step of forming the lower lug support plate may further include the step of forming a plurality of fixed shredder lugs and tumbling spikes. The lower lug support plate may further be heat treated after the forming step.
The step of forming the stationary shredder ring may include cold stamping the ring from a sheet or strip of metal, although other methods may be used such as powered metal methods, injection molding methods, and casting methods.
The enclosure may include a dishwasher inlet and a plurality of diverters that are rounded and/or smooth in shape. The rounded diverters may be located adjacent to the dishwasher inlet.
The above summary of the present invention is not intended to represent each embodiment, or every aspect of the present invention. This is the purpose of the figures and detailed description which follow.